View clinical trials related to Refractive Errors.
Filter by:To assess the improvement in refractive error and the corneal endothelial safety with a customized corneal crosslinking treatment regimen for low grade myopia. The study compares two treatment protocols, a 4.0-mm central ring-shaped zone with a 3.5-mm central ring-shaped zone in high oxygen environment without corneal epithelial debridement.
Some programs do the screening, refraction testing and provision of spectacles to children entirely in the school setting ("School Model"). One strength of such programs is that most children at school who need spectacles get them. However, sustainability is poor, because spectacles cannot be sold in many schools and there may be too few refractionists to cover all schools in most countries. Other programs provide vision screening at schools but refer children who fail vision screening to nearby facilities for refraction and distribution/sale of spectacles ("Referral Model"). This model's strengths include a lower demand for refractionists and opportunities for the spectacles to be sold. However, a disadvantage is that most of the referred children do not attend the specialist facility. One way to improve this might be to enhance the Referral Model and a recent USAID review by Priya Reddy and Ken Bassett showed that involving teachers in vision screening and family counseling significantly increases children's use of spectacles. Therefore, at 141 schools in India, involving over 42,300 children (assuming a minimum of 300 children/school), the investigators will study an "Improved Referral Model," with strong teacher involvement, to investigate the potential benefits of combining the lower costs of the "Referral Models" with the high uptake of the "School Model". The investigators will also assess the effects of allowing parents to purchase enhanced spectacles, rather than having their child use free spectacles. Children will be randomized by the school to the "School Model," "(Improved) Referral Model" or the "(Improved) Referral Model + Cost Recovery (sale of "upgrade spectacles" alongside offering free spectacles. The main study outcome will be program cost-effectiveness, defined as the program cost per child identified with correctable refractive error, who receives spectacles, and wears them at an un-announced visit between 8 to 12 weeks after distribution. Profit on spectacles sold in the "Referral + Cost Recovery" group will be subtracted from the program costs in this study group. The groups will be compared, with and without adjustment for baseline characteristics.
The objective of this clinical investigation is to collect valid scientific safety and effectiveness data on the Acuity 200 (fluoroxyfocon A) Rigid Gas Permeable Contact Lens, manufactured from a newly developed rigid gas permeable material that is highly permeable to oxygen. The clinical performance data reported from this study is intended to be submitted to the U.S. Food and Drug Administration Center for Devices and Radiological Health (CDRH) in support of a 510(k) premarket notification.
The Lentechs Apioc-S and Apioc-A contact lenses are made in an FDA-approved contact lens material indicated for single-vision and astigmatism. The novel lens design has a lenticular portion which is thicker than the optical portion of the lens. When applied to the eye, it is oriented in a superior position. Unlike contact lenses currently on the market, this innovative design improves lens stability by preventing lens rotation, and may improve tear flow behind the lens.
The purpose of this study is to evaluate end of day (EOD) visual acuity (VA) at distance when wearing Precision1™ contact lenses compared to Acuvue® Moist contact lenses.
Single-center, open-label, prospective study in healthy volunteers desiring refraction for correction of visual acuity to compare a handheld device supported by a mobile application with the phoropter and autorefractor.
The purpose of this clinical study is to demonstrate the safety and performance of an investigational soft contact lens compared to a commercially available soft contact lens when worn in a daily wear modality.
There is a great need for precise and repeatable measurements of the choroidal thickness. Including the diurnal physiological changes, accommodation and refractive error impact on those measurements.
Refractive surgeries can be divided into two distinct categories: 1) corneal surgeries (superficial and deep procedures) carried on the surface of the eye and 2) lens surgeries (phakic IOL, refractive lens exchange) - an intraocular intervention, performed in the anterior or posterior chamber or on the lens. In the proposed protocol focus is on the corneal refractive surgeries impact on monochromatic higher-order aberrations on the one hand and chromatic aberrations on the other. During the surgery in order to get the patient emmetropic, refractive surgery corrects optical defects by decreasing aberrations of lower orders ) simultaneously increases high-order aberrations (that is perceived by the patient as halo, glare or starburst). Informations about prevalence and causes of higher order aberrations after refractive surgery are numerous but there is no information about chromatic aberrations.
The purpose of this study was to evaluate visual acuity at distance when wearing DDT2 contact lenses compared to Clariti contact lenses.